The explosion in the use of three anti-anemia drugs to treat cancer and kidney patients illustrates much that is wrong in the American pharmaceutical marketplace. Thanks to big payoffs to doctors, and reckless promotional ads permitted by lax regulators, the drugs have reached blockbuster status. Now we learn that the dosage levels routinely injected or given intravenously in doctors’ offices and dialysis centers may be harmful to patients.

As Alex Berenson and Andrew Pollack laid bare in The Times on May 9, wide use of the medicines — Aranesp and Epogen, from Amgen; and Procrit, from Johnson & Johnson — has been propelled by the two companies paying out hundreds of millions of dollars in so-called rebates. Doctors typically buy the drugs from the companies, get reimbursed for much of the cost by Medicare and private insurers, and on top of that get these rebates based on the amount they have purchased.

Although many doctors complain that they barely break even or even lose money on the costly drugs, for high-volume providers the profits can be substantial. One group of six cancer doctors in the Pacific Northwest earned a profit of about $1.8 million last year thanks to rebates from Amgen, while a large chain of dialysis centers gets an estimated 25 percent of its revenue, and a higher percentage of its profits, from the anemia drugs. It seems likely that these financial incentives have led to wider use and the prescribing of higher doses than medically desirable.